feat: auth service + security audit fixes + cleanup legacy services

Major changes:
- Add auth-svc: JWT auth, register/login/refresh, password reset
- Add auth UI: modals, pages (/login, /register, /forgot-password)
- Add usage tracking (usage_metrics table, daily limits)
- Add tiered rate limiting (free/pro/business)
- Add LLM usage limits per tier

Security fixes:
- All repos now require userID for Update/Delete operations
- JWT middleware in chat-svc, llm-svc, agent-svc, discover-svc
- ErrNotFound/ErrForbidden errors for proper access control

Cleanup:
- Remove legacy TypeScript services/ directory
- Remove computer-svc (to be reimplemented)
- Remove old deploy/docker configs

New files:
- backend/cmd/auth-svc/main.go
- backend/internal/auth/{types,repository}.go
- backend/internal/usage/{types,repository}.go
- backend/pkg/middleware/{llm_limits,ratelimit_tiered}.go
- backend/webui/src/components/auth/*
- backend/webui/src/app/(auth)/*

Made-with: Cursor

backend/webui/src/app/(auth)/register/page.tsx

@@ -0,0 +1,58 @@
+'use client';
+
+import { useEffect } from 'react';
+import { useRouter } from 'next/navigation';
+import Link from 'next/link';
+import { RegisterForm } from '@/components/auth';
+import { useAuth } from '@/lib/contexts/AuthContext';
+
+export default function RegisterPage() {
+  const router = useRouter();
+  const { isAuthenticated, isLoading } = useAuth();
+
+  useEffect(() => {
+    if (!isLoading && isAuthenticated) {
+      router.push('/');
+    }
+  }, [isAuthenticated, isLoading, router]);
+
+  if (isLoading) {
+    return (
+      <div className="min-h-screen bg-base flex items-center justify-center">
+        <div className="w-8 h-8 border-2 border-accent border-t-transparent rounded-full animate-spin" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="min-h-screen bg-base flex flex-col">
+      <header className="p-4">
+        <Link href="/" className="inline-flex items-center gap-2 text-lg font-semibold text-primary">
+          <div className="w-8 h-8 rounded-lg bg-accent/20 flex items-center justify-center">
+            <span className="text-accent font-bold">G</span>
+          </div>
+          GooSeek
+        </Link>
+      </header>
+
+      <main className="flex-1 flex items-center justify-center px-4 py-8">
+        <div className="w-full max-w-md">
+          <div className="bg-elevated border border-border rounded-2xl p-8 shadow-xl">
+            <RegisterForm
+              showTitle
+              onSuccess={() => router.push('/')}
+              onSwitchToLogin={() => router.push('/login')}
+            />
+          </div>
+
+          <p className="text-center text-sm text-muted mt-6">
+            Уже есть аккаунт?{' '}
+            <Link href="/login" className="text-accent hover:text-accent-hover font-medium">
+              Войти
+            </Link>
+          </p>
+        </div>
+      </main>
+    </div>
+  );
+}